THIS INVENTION relates to the production of oxygenated products. It relates in particular to a process for producing oxygenated products from an olefinic feedstock, and to a hydroformylation catalyst.
Hydroformylation processes for the production of oxygenated products, particularly aldehydes and/or alcohols, by the reaction of an olefinic feedstock with carbon monoxide and hydrogen at elevated temperatures and pressures in the presence of hydroformylation catalysts, are well known. The alcohols and/or aldehydes that are produced in these processes generally correspond to the compounds obtained, in the hydroformylation reaction, by the addition of a carbonyl or carbinol group to an olefinically unsaturated carbon atom in the feedstock with simultaneous saturation of the olefin bond.
A hydroformylation catalyst is selected according to the particular oxygenated products which are required from a particular olefinic feedstock. Thus, the hydroformylation catalyst may typically be a phosphine and/or phosphite ligand modified rhodium (Rh) or cobalt (Co) homogeneous catalyst. Examples of such catalysts are triphenyl phosphine ligands used with rhodium, and alkyl phosphine ligands used with cobalt. Specific examples of the latter are trialkyl phosphines and bicyclic tertiary phosphines such as 9-phosphabicyclo [3.3.1] nonane and 9-phosphabicyclo [4.2.1] nonane represented by formulas (I) and (II) respectively: 
The ligands I and II are available commercially, as a mixture, under the collective chemical name eicosyl phoban (xe2x80x98EPxe2x80x99).
A disadvantage of Co catalysed hydroformylation processes is the number of unwanted side reactions that result in the formation of undesirable side products, such as heavy ends and paraffins. These products not only impact negatively on the design of commercial processes but furthermore decrease the yield of the desirable and commercially valuable alcohol and/or aldehyde products from such a process.
Although phosphine-modified Co catalysed hydroformylation affords improved selectivity towards linear alcohols, another disadvantage is that reaction rates are generally far lower than those obtained with unmodified Co catalysis.
It is hence an object of this invention to provide a process for producing oxygenated products from an olefinic feedstock, whereby these problems are at least reduced.
Thus, according to a first aspect of the invention, there is provided a process for producing oxygenated products from an olefinic feedstock, which process includes reacting, in a hydroformylation reaction stage, an olefin feedstock with carbon monoxide and hydrogen at elevated temperature and superatmospheric pressure in the presence of a hydroformylation catalyst comprising a mixture or combination of a metal, M, where M is cobalt (Co), rhodium (Rh), ruthenium (Ru) or palladium (Pd); carbon monoxide; and a bicyclic tertiary phosphine having a ligating phosphorus atom, with the ligating phosphorus atom being neither in a bridgehead position nor a member of a bridge linkage, to produce oxygenated products comprising aldehydes and/or alcohols.
The metal, M, may be any one of cobalt, rhodium, ruthenium or palladium; however, cobalt is preferred.
In particular, the bicyclic tertiary phosphine of the hydroformylation catalyst may be a [3.3.1]phosphabicyclononane represented by formula (III): 
where
R1 is an alkyl, branched alkyl, cycloalkyl, or aryl group;
R2 is an alkyl group; and
R3 is an alkyl group.
More particularly, R1 of the [3.3.1]phosphabicyclononane of formula (III) may be a linear C2 to C20 hydrocarbon chain; and R2=R3. Still more particularly, R2 and R3 may each be methyl.
The family of ligands of formula (Ill) in which R2=R3=methyl is named Lim (as these ligands are limonene derived); thus, each ligand can be denoted xe2x80x98Limxe2x80x99, together with a suffix corresponding to the carbon number of R1. In one embodiment of the invention, the ligand may be Lim-18. Thus, Lim-18 will be represented by the formula IV, where R1 is C18H37. 
In another embodiment of the invention, the ligand may be Lim-10. In other words, R1 of the [3.3.]phosphabicyclononane of formula (III) is then C10H21.
The reaction temperature may be from 100xc2x0 C. to 300xc2x0 C., typically from 150xc2x0 C. to 200xc2x0 C.
The reaction pressure may be at least 20 bar (150 psi), preferably between 50 bar (750 psi) and 100 bar (1500 psi), typically about 85 bar (1232 psi).
The hydroformylation reaction stage may be provided by a reactor capable of handling a homogenously catalysed chemical transformation, such as a continuous stirred tank reactor (xe2x80x98CSTRxe2x80x99), bubble column, or the like.
The olefinic feedstock may, in particular, be a C2 to C20 Fischer-Tropsch derived olefin stream. Thus, the olefinic feedstock may be that obtained by subjecting a synthesis gas comprising carbon monoxide and hydrogen to Fischer-Tropsch reaction conditions in the presence of an iron-based, a cobalt-based or an iron/cobalt-based Fischer-Tropsch catalyst, with the resultant olefinic product then constituting the olefinic feedstock of the process of the invention, or a component thereof constituting the olefinic feedstock of the process of the invention.
In other words, the olefinic product from the Fischer-Tropsch reaction can, if necessary, be worked up to remove unwanted components therefrom and/or to separate a particular olefinic component therefrom, with said particular olefinic component then constituting the olefinic feedstock of the process of the invention.
According to a second aspect of the invention, there is provided a hydroformylation catalyst which includes, as a first component, a metal M, where M is cobalt, rhodium, ruthenium, or palladium; as a second component, carbon monoxide; and, as a third component, a bicyclic tertiary phosphine having a ligating phosphorus atom, with the ligating phosphorus atom being neither in a bridgehead position nor a member of a bridge linkage, to produce oxygenated products comprising aldehydes and/or alcohols, with the components being in the form of a mixture.
The metal M and the bicyclic tertiary phosphine may be as hereinbefore described with respect to the first aspect of the invention.
The invention will now be described by way of example, with reference to the following drawings.